The U.S. Department of Energy estimates that the ocean floor and arctic permafrost regions contain several trillion cubic feet of methane gas (also referred to as natural gas) in the form of methane hydrates. Methane hydrates are clathrate compounds which are inclusion complexes formed at high pressures and low temperatures, existing as solid crystalline structures. In these structures, methane gas molecules are surrounded or included by a cage of water molecules. Methane hydrates are typically found on the ocean floor in sediments which are stable at depths of approximately 300 meters.
There is increasing interest in the development of methods to extract methane gas from formations containing methane hydrates. The production of methane gas is viewed as one means for lessening global dependency on oil and other fuels containing large amounts of carbon. Efforts to increase methane gas production are also motivated by an expanding natural gas infrastructure and growing interest in natural gas from public utility companies. At least one extraction technique, solvent injection, has been proposed and tested to extract methane gas from methane hydrates. Although solvent injection has shown promise, the technique is difficult to apply uniformly through a formation, and may not be suitable for deep formations. As a result, currently proposed techniques for extracting methane gas from methane hydrate formations leave much to be desired.